﻿<?php
 
$res=distanceBetween(120.4103540,36.2938350,120.4103740,36.2937730);
var_dump($res);

/**  * @desc 根据两点间的经纬度计算距离  * @param float $lat 纬度值  * @param float $lng 经度值 */
function getDistance2($lat1, $lng1, $lat2, $lng2)
{
    $earthRadius = 6367000;
//approximate radius of earth in meters    /*  Convert these degrees to radians  to work with the formula  */   
    $lat1 = ($lat1 * pi()) / 180;
    $lng1 = ($lng1 * pi()) / 180;
    $lat2 = ($lat2 * pi()) / 180;
    $lng2 = ($lng2 * pi()) / 180;
    /*  Using the  Haversine formula    http://en.wikipedia.org/wiki/Haversine_formula    calculate the distance  */
    $calcLongitude = $lng2 - $lng1;
    $calcLatitude = $lat2 - $lat1;
    $stepOne = pow(sin($calcLatitude / 2), 2) + cos($lat1) * cos($lat2) * pow(sin($calcLongitude / 2), 2);
    $stepTwo = 2 * asin(min(1, sqrt($stepOne)));
    $calculatedDistance = $earthRadius * $stepTwo;
    return round($calculatedDistance);
} 
/**
 * 计算两个坐标之间的距离(米)
 * @param float $fP1Lat 起点(纬度)
 * @param float $fP1Lon 起点(经度)
 * @param float $fP2Lat 终点(纬度)
 * @param float $fP2Lon 终点(经度)
 * @return int
 */
function distanceBetween($fP1Lat, $fP1Lon, $fP2Lat, $fP2Lon){
    $fEARTH_RADIUS = 6378137;
    //角度换算成弧度
    $fRadLon1 = deg2rad($fP1Lon);
    $fRadLon2 = deg2rad($fP2Lon);
    $fRadLat1 = deg2rad($fP1Lat);
    $fRadLat2 = deg2rad($fP2Lat);
    //计算经纬度的差值
    $fD1 = abs($fRadLat1 - $fRadLat2);
    $fD2 = abs($fRadLon1 - $fRadLon2);
    //距离计算
    $fP = pow(sin($fD1/2), 2) +
          cos($fRadLat1) * cos($fRadLat2) * pow(sin($fD2/2), 2);
    return intval($fEARTH_RADIUS * 2 * asin(sqrt($fP)) + 0.5);
}
/**
 * 百度坐标系转换成标准GPS坐系
 * @param float $lnglat 坐标(如:106.426, 29.553404)
 * @return string 转换后的标准GPS值:
 */
function BD09LLtoWGS84($fLng){ // 经度,纬度
    $lnglat = explode(',', $fLng);
    list($x,$y) = $lnglat;
    $Baidu_Server = "http://api.map.baidu.com/ag/coord/convert?from=0&to=4&x={$x}&y={$y}";
    $result = @file_get_contents($Baidu_Server);
    $json = json_decode($result);
    if($json->error == 0){
        $bx = base64_decode($json->x);
        $by = base64_decode($json->y);
        $GPS_x = 2 * $x - $bx;
        $GPS_y = 2 * $y - $by;
        return $GPS_x.','.$GPS_y;//经度,纬度
    }else
        return $lnglat;
}
$r=BD09LLtoWGS84('120.4103540,36.2938350');

var_dump($r);

